Machine for obtaining an image



Jan. 21, 1964 F. P. ALLES MACHINE FOR OBTAINING AN IMAGE 2 Sheets-Sheet 1 Filed April 10, 1961 INVENTOR FRANCIS PETER ALLES ATTORNEY Jan. 21, 1964 F. P. ALLES MACHINE FOR OBTAINING AN IMAGE 2 Sheets-Sheet 2 Filed April 10, 1961 FIG-6 FIG.5

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FIG-7 INVENTOR 6 FRANCIS PETER ALLES BY 73M M ATTORNEY United States Patent Ofiice 3,313,?!3 Patented clan. 21, 1954 3,118,178 MACHINE FER @BTAlNING AN IMAGE Francis Peter Alles, Westfield, Ni, assignor to E. I. du Pont de Nemours and Company, Wilmington, Dei., a corporation of Delaware Filed Apr. 10, 1961, Ser. No. 101,980 6 Claims. (Cl. 18-5) This invention relates to a machine for obtaining a. clear or light-transmitting image in an opaque pressure claiifiable film. More particularly, it relates to such a machine for obtaining such an image from a printing form and which can be used as a process transparency to expose a photosensitive printing plate.

In Bechtold US. Patent 2,957,791 a method is described for selectively clarifying the opaque, pressure clarifiable films covered by said patent by pressing the films against a copper engraving, by placing the film in a typewriter, without an inking ribbon, and typing directly on it, and by other methods. The resultant clear imagebearing elements can then be used as negatives for photoprinting. The pressure clarifiable films can be placed against type in a proofing press, and the roller passed over the type to produce a clear image of the type in the film.

An object of this invention is to provide a simple and elfective machine for subjecting opaque, pressure clarifiable films to image transfer contact with a relief image. A related object is to provide such a machine for subjecting such films to contact with relief printing forms, e.g., type matter, and or halftones. Yet another object is to provide such a machine which results in clear, sharp images which faithfully reproduce the surface of the relief printing form. A further object is to provide such a machine which i simple in construction, easy to operate and gives uniform, depend-able results. A still further object is to provide such an apparatus which can be manufactured economically.

The machine of this invention comprises a shallow box frame having side and end rails, a bottom and an open top adapted to receive a relief printing form, a separate frame member adapted to travel from one extremity to another extremity of the box frame carrying a rotary ii rpeller extending transversely of said box frame, said impeller having rows of circumferentially mounted inpact elements of small impact surface area, said rows being rotatable about a centrally-disposed common axis, said impact elements being adapted to move toward and away from said axis and in small arcs from the axis of their respective rows. The impeller preferably has a pluraliy of rows of said impact elements and is rotatably mounted so that the impact elements of each row are brought into impact relation-ship with a point or plane at about the surface of the relief as the impeller traverses the box frame. Thus, the impact elements are capable of extending below and above the position of the relief in their extended and retracted positions, respectively. Also, the box frame can be provided with means for reducing pressure (i.e., forming a vacuum.) in the box frame.

The impeller unit constitutes an important aspect of the invention and can be used with other frames supporting a printing form.

A novel machine or" this invention will now be described with reference to the attached drawings which form a part of this application.

Referring to the drawings:

FIG. 1 is a perspective view of a machine of this invention with a printing relief, opaque pressure clarifiable film and cover film in operative relationship, showing one type of impeller;

,. FIG. 2 is a vertical section along the ine 22 of PEG.

1 with parts in elevation;

FIG. 3 is an elevation of one kind of impeller and one kind of impact element, with parts in section;

FIG. 4 is an end elevation taken dong the line 4-4 of FIG. 3 of the impeller;

FIG. 5 is an enlarged elevation of a fragment of the impeller with a modified impact element;

FIG. 6 is an enlarged elevation of a fragment of an impeller with -a different modified impact element;

FIG. 7 is an enlarged elevation of a fragment of an impeller with a modified support member and different impact element; and

FIG. 8 is an enlarged elevation of a fragment of an impeller with an alternative (impact element.

Referring now to the drawings wherein the same reference numerals refer to the same parts throughout the several views, the machine of this invention embodies two coacting units. The first unit is a shallow box type frame 21 having side rails 22, end rails 23 and a closed bottom 24. If desired, the upper surfaces of the s ide and end rails can be provided with a channel which extends around the periphery of the frame. This channel 25 is provided with a lateral eduction duct 25. Similarly, the bottom is provided with an eduction duct 27. These ducts are connected to eduction pipes 23 which can be joined or separately connected to a vacuum pump or other source of vacuum, not shown. The shallow box frame is adapted to receive a printing form 29 and the height of the rail is generally adjusted so that the surface of the printing form is in about the plane of the top of the rails. In use, an opaque, pressure clarifiable film 3% is placed on top of the printing form and is covered with a cover sheet 31, preferably transparent.

The second unit of the machine embodies an impeller with .centrifugally actuated impact members. It comprises a transverse frame 32 which is Wider than the box frame. The transverse frame has depending side arms 33 in which there is journalled near one corner at the bottom a shaft 34 which extends between the side arms. This shaft carries a transverse supporting roller 35. in the opposite corners of the depending side arms there is journ-alled another shaft 36 which likewise extends between tlie side arms and has a second support roller 37 mounted thereon. A rotary impeller 38 is also journalled in the side arms between the above shafts 34 and 36 by means of stub shafts 39. This impeller has a central hub to and end flanges 41 :which are provided with holes which are used to support rods 3 extending between the flanges. These rods preferably have threaded ends so that they can be tightly secured to the flanges. On each rod there are assembled, or strung, a series of individual impact elements 46 and these elements are capable of movement freely in an arcuate and up and down direction on the rods.

Motor 47 is afilxed to the upper surface of transverse frame 32. This motor, which preferably is an electric motor of the reversing type, has a central drive shaft 43 extending from each of its sides, and one end of the shaft is connected through coupling 4-9 to a connecting shaft 50 which in turn is joined through coupling 51 to stub shaft 52. on reducing gear box 53, also mounted on the transverse frame. The other end of the gear box is pro vided with a drive shaft 54 on which is mounted pulley 55 carrying belt 56 which fits into pulley 57 attached to the end of roller shaft 36. )n the other end of the drive shaft of the motor there is fastened a drive pulley 58 on which is mounted belt 59 which fits into pulley 6d atfixed to one of the stub shafts 39 of the rotary impeller With reference to FIGS. 4, 5 and 6 of the drawings the impact elements are, in their simplest form, thin, loosely fitting washers which may be composed of metal or plastic material. Suitable materials include steel, copper, brass, various ferrous metal alloys, stainless steel and polymers.

titanium; nylon, polytetra'lluoroethylene, cellulose acetate, cellulose propionate, high density polyethylene, polypropylene, polyethylene terephthalate, polyformaldehyde, phenol formaldehyde, melamine, or other resins or super- Self-lubricating plastic materials, e.g., nylon or polytetrafluoroethylene are preferred.

As shown in PEG. 3, these washers have straight side walls and their peripheral surfaces are perpendicular to the side walls. However, the peripheral surface need not be perpendicular but may be curved or rounded. These impact elements, i.e., washers or rings, can have a protruding portion, or portions, of various shapes, and two representative forms of protuberances are shown in FIGS. 5 and 6. A practical thickness of the impact elements, in Washers, is from 5 to 59 mils LOGS-.05 inch).

it will be noted that the impact elements have holes which are of greater diameter than that of the supporting rods 43 and this allows them to swing in an arcuate direction, thereby imparting centrifugal force, and in an up or down or axial direction after impact.

These supporting rods 43 may, of course, have various shapes, and instead of beinga uniform diameter throughout their length and through the flanges may be reduced in diameter or size near their ends so that a shoulder will abut the flanges.

instead of round, solid rods there, of course, ma be used hexagonal or other shaped rods but the round rods are preferred. The rods may be solid or have hollow centers, that is, they may be tubes. These rods or tubes can be fastened to the flanges of the impeller in various ways.

in FIGS. 7 and 8 the supporting rods are hollow tubes of having a longitudinal slot 62. In this alternate form of the invention, the impact elements may be narrow discs 63 of small diameter, as shown in FIG. 7, or they may be arcuate sections of small width having depending ends, as shown in H6. 8. In these two latter forms, the discs, or arcuate impact elements, extend beyond the slot so as to provide an impact or striking surface beyond the normal path of the tubes.

The impact elements, as previously stated, are narrow in thickness and can vary in thickness from 5 to 50 mils. if desired, there can be placed between the impact elements, or at'the ends of'the row of impact elements, various washers or spacers which are smaller in diameter and cannot serve as impact elements. The spacers may be of the same thickness as the impact elements or smaller in thickness, and the spacers of one row can differ from those in another row. Also, the impact elements on one row preferably are spaced differently than those on an adjacent or other row so that they have an overlap impact action. This can be accomplished by inserting washers, or spacers, at one end of one row and none on the next row, or by having washers at both endsof a row of impact elements. P or instance, if spacers are used on alternate rods and no spacers are present on intervening rods, then there may be an overlap impact arrangement. Various other arrangements of spacers can be used to produce different patterns of impact. in one case, for example, spacers exactly half the width of an individual impact member could be placed at one end of alternate rods, or two spacers could be placed at one end of alternate rods and one at each end of the intervening rods. By appropriate selection of spacer width [thickness] and arrangement, it is obvious that a wide variety of impact patterns can be obtained. 7

Instead of having driving belts and pulleys there can, of course, be substituted sprockets and cha ns or other meshing gear trains. Also, other means for driving the impeller and one of the support rollers can :be used instead of that shown in FIG. 1. Moreover, by rearranging the position of the impeller shaft and that of the support rollers, the impeller unit can bemodified so as to run on a curved track rather than ona flat, track. Similarly, by adding sprockets and racks to the impeller unit and to the 4 unit holding the printing form, respectively, the apparatus may be reconstructed so as to be useful on cylindrical printing forms.

The machine of this invention, as described above and illustrated in the drawings can be operated as follows.

Jitn reference to FIGS. 1 and 2, a relief printing form 2?, e.g., a block of type, halftone plate or a plate containing both line and halftone reliefs, is placed with the relief face upward in the box frame 21. The upper surface of this relief, as shown in FIG. 2, is in a common plane with the upper surface of the rails of said frame. A sheet of opaque pressure clarifiable film 39 is laid face down on no upper surface of the printing form. This film, for example, may have a 2-mil thick polyethylene terephthalate film base and a coating about /2 mil in thickness of an opaque, porous, pressure clarifiable material. This coating faces the upper surfaces of the printing form. A sheet of transparent polyethylene terephthalate film 2 to 4 mils in thickness is then placed in surcontact with the pressure clarifiable film. The latter film constitutes the transparent cover sheet 31 referred to above. The pressure clarifiable film should cover at least the entire area of the printing form to be reproduced and may overlap the side and end railsof the box frame. In either event, the protective cover sheet should cover the entire upper surface of the frame and preferably overlaps the edges of the side and end rail Upon inducing a vacuum in the box frame, the pressure ciarifiable film is held firmly in place on the surface of the printing form. The impeller unit of the apparatus is then placed above the cover sheet 3 and support rollers 34 and 37 rest on the side rails with the protective cover sheet and, in some instances, also the pressure clarifiablefilm being interposed between the surfaces of the feed rollers and the rails. When the desired degree of reduced pressure is obtained, motor 47 is actuated and it, through the coupling, drive shaft, gear reduction box, pulleys and belts, rotates one of the support rollers, causing the unit to traverse the box franc from one end toward the other. Concurrently, the motor, through connecting pulleys and belts, causes the rotary impeller 38 to rotate. As the impeller rotates, the impact elements 46 likewise rotate about the axis of the impeller. The impeller is arranged to rotate at many times the rate of rotation of roller shaft 36, the ratio of speed of rotation being determined by the size of the pulleys and the ratio of the reducing gear box. For example, the impeller may rotate at a speed of 1604000 revolutions per minute while roller shaft 34 rotates at a speed sufficient for the supporting roller 35 to traverse along the box frame at a linear speed of 4 inches to 40 inches per minute.

Upon rotation of the impeller, the impact members are thrown outwardly from their central axes bycentrifugal force; hence, as each of the rods 43 approaches the lowermost position of its travel the impact elements strike the surface of the protective cover sheet 31 and subject it to a series or multiplicity of small stresses or pressures across its width. The impact force, or pressure, in each instance will be a function of the speed of rotation of the impeller and the mass and distance of the impact elements from the axis of the impeller.

The distance between the axis of the impeller shaft and the surface of the transparent cover sheet should be such that if the impact members were in their fully reracted position they would clear the surface of said sheet;

but in their extended position, while rotating and under centrifugal force, will hit or contact the cover sheet and subject it to momentary localized pressure. The speed of the impeller should be so related to that of roller shaft 34 that the area of the impact of impact elements as on each succeeding rod 43 will overlap the area of impact of such elements on the preceding rod to a slight (predetermined) extent; By having the impact elements in one row offset laterally from those in another row, a controlled pattern of impact can be attained.

The various structural parts of the box frame and of the impeller unit can be made of conventional materials of construction. For most of the members and parts, steel, steel alloys, brass and aluminum can be used.

if desired, the driving means for one of the support rollers can be eliminated and the box frame holding the printing form can be moved along the axis While the impeller is rotated independently.

Various types of pressure clarifiable films can be used in the apparatus of this invention. As previously stated, suitable pressure clariiiable films are described in Bechtold US. Patent 2,957,791. Other useful supported and unsupported pressure clarifiable films are described in US. Patents 2,846,727, 2,848,752, and in assignees US. application Ser. No. 63,953Oct. 21, 1960.

The opaque pressure-clarifiable films described in Bechtold U.S.P. 2,957,791 and in the Bechtold patents referred to therein, have also been called opaque pressure coalescible films and these films may also be termed opaque pressure clearable films since the opaque areas which are highly opaque are converted by means of pressure into clear areas readily transparent to visible light. The films are also clearable by heat and by heat and pres sure.

The films or coatings of the Bechtold patents which constitute prefer-red materials for use in this invention are porous, opaque, non-fibrous, of low bulk density and are composed of partially coalesced discrete particles of a hydrophobic organic addition polymer having a Wholly carbon chain, a molecular Weight of at least 10,000 and being taken from the group consisting of vinyl and vinylidene addition polymers, said film having an open-cell structure characterized by microscopic voids communicating wit the surface and containing 20% to 80% by volume of openell pores, said film having a permeability to Water vapor of about times greater than that of corresponding non-porous films of the same polymer and thickness, the opacity per unit of thickness being such that a film thickness of 3 mils and greater has a light-transmission of less than 10% at 4000 A., and increased light transmission at longer Wavelengths of light, said film being capable of sustaining a permanent reduction in thickness of at least 20% together with substantial clarification of opaqueness under a pressure of 10,000 pounds per square inch :at room temperature. These films are more fully described and defined in Be'chtold U.S.P. 2,957,791 which constitutes part of this disclosure.

After the clarified, or clear, images are formed in the opaque pressure clearable films in accordance with this invention, the unclarified background areas can be increased in optical density by deposition of opaque material in such areas to provide a high-contrast irnagebearing layer. These areas being porous are readily coated or impregnated with colorants which fill the open cell voids. Any of the post-densification procedures described in assignees Bechtold US. application Ser. No. 63,953 can be used. Thus, the selectively clarified coating can be post-densified in unchanged opaque background areas by in situ deposition of lead sulfide at 50 C. by immersing the coating in aqueous lead nitrate and sodium sulfide solutions with intermediate blotting with porous cardboard, wa hing in water and drying which gives a dense, black background. Alternatively, the background areas can be post-densified by dyeing for several minutes with 2.5% aqueous solution of an after chromed dye, Colour Index No. 15,710, at 50 C. for several minutes.

The machine can be provided with various electrical control means for energizing and de-energizing the electric motor to start and stop the machine or to reverse it. Limiting switches can be placed near the ends of the box tray to reverse the motor.

The machine of this invention in its broader aspects comprises means for holding an object having a surface to be treated, a separate frame adapted to travel in a elected path with respect to said surface, a rotary impeller carried by said frame to extend transversely of said surface, said impeller having a plurality of transverse rows of individual impact elements of small size, said rows being adapted to rotate in a circular path around the axis of said impeller and said individual impact elements being adapted to move toward and away from said circular path and in small arcs from the axis of the respective rows on which they are mounted, the impacting surfaces of said impact elements being capable of extending below and above the surface to be treated in their extended and retracted positions, respectively, said frame and separate frame having coacting guiding means.

The dimensions and arrangement of the parts of the machine can be varied to accommodate a number of factors such as the size of frame and printing form held by it and the ratio of number of impacts desired to the speed of traverse. In addition, other modifications may be made in the configuration of the parts of the machine.

For example, the bearings for the impeller and support roller shafts can be fixed, as shown, or made adjustable. By making them vertically adjustable, the clearance between the rotatable stress applying means and the surface of the printing form can be changed as desired. This will, in turn, permit variation in the area of contact between the individual impact members and the surface treated.

Also, the individual rods 4-3 can be inserted through slots in the flanges and their distance from the axis of the impeller varied. The level of the printing relief, e.g., type face, also can be adjusted to bring it into the same plane as the side rails of the frame for the printing relief, e.g., by the use of paper, metal, or other shims.

While the eight rods 4-3 are shown in the drawings, a lesser or greater number can be used. They should be spaced sufficiently to give adequate clearance between the impact members of adjacent rows. This can be accomplished to a considerable degree by adjusting the diameter or" the flanges.

The ratio between the speed of the impeller and the speed of the support roller can be varied by changing either the sizes of the pulleys or the ratio of the reduction gear box. A speed changing device can be placed between the motor and the reduction gear box.

The machine of this invention has the advantage that it is simple in construction but dependable in operation. When used as described above, it will faithfully reproduce a printing relief forming a clear and transparent image of the relief in the opaque pressure clarifiable film element. The machine had the (advantage that it is readily adaptable for obtaining photographic negatives or transparencies from a Wide variety of printing reliefs including type forms, engraved plates, photo-polymerized printing reliefs, halftones, combined halftones and line printing forms, etc.

Another advantage is that the various parts of the machine are simple in construction, easy to assemble, require little attention to keep them in operative condition, and have good wearing properties. A furtier advantage is that the machine does not require much space and is relatively inexpensive. The box frame is of very simple construction and like that of a conventional vacuum frame.

By placing small sheets or blocks under the printing form, various heights of such forms can be accommodated which is a further advantage.

A particular advantage of the invention is that it permits one to rapidly convert a printing relief into a photographic transparency, accurately reproducing as a clear image all of the fine details of the relief. The machine has an additional advantage that it does not damage the surface of the relief or type form and gives an adequate clear image in an opaque pressure clarifiable film in a short time. It avoids the use of heavy pressure rollers such as those used in pulling a proof from a bed of type which often damages the type surface and cannot be successfully used where fine rulings are in the printing surface. Still further advantages will be apparent from the foregoing description and accompanying drawings.

I claim:

1. A machine for obtaining clear images in opaque, pressure-clearable film comprising a shallow box frame having side rails, end rails, a bottom and an open top adapted to receive a printing form; a separate frame member adapted to travel from one extremity to the other extremity of said box frame and having a rotary impeller extending transversely of said box frame, said impeller having a plurality of transverse rows of circumferentially mounted impact elements of small surface area, said rows be ng adapted to travel in a circular path about a centrally-disposed common axis and said impact elements being adapted to move toward and away from said path and in small arcs from the axis of the respective rows on which they are mounted, the impacting surfaces of said elements being capahle'of extending below and above the position of the relief of the printing form in their extended and retracted positions, respectively, the impact elements in one row being spaced differently than the impact elements in another row so that they have an overlap impact action.

2. A machine according to claim 1 wherein said impact elements are washers having a thickness of 5 to 50 mils.

3. A machine according to claim 1 wherein the upper surface of said side and end rails has an air removal channel and said shallow box frame has means for removing air therefrom.

4. A machine according to claim 1 wherein said separate frame has mounted thereon a motor and means for driving a support roller and said impeller by said motor.

5. A machine according to claim 1 wherein said separate frame carries spaced support rollers which are adapted to travel along said side rails and means for slowly rotating a support roller to traverse said separate frame.

6. A machine according to claim 5 wherein said separate frame has depending arms and the rotary impeller and the support roller extend between and are journalled in said arms.

References Cited in the file of this patent UNITED STATES PATENTS 800,962 Wattles Oct. 3, 1905 1,030,837 Ashton June 25, 1912 1,060,875 Wood May 6, 1913 1,146,853 Dick July 20, 1915 1,910,986 Cook May 23, 1933 1,914,442 Lawson June 20, 1933 2,088,402 Borck July 27, 1937 2,639,741 Taylor et a1. May 26, 1953 2,957,791 Bechtold Oct. 25, 1960 2,991,600 Lancaster July 11, 1961 3,060,507 Knowles Oct. 30, 1962 FOREIGN PATENTS 281,886 Germany -a Feb. 5, 1915 

1. A MACHINE FOR OBTAINING CLEAR IMAGES IN OPAQUE, PRESSURE-CLEARABLE FILM COMPRISING A SHALLOW BOX FRAME HAVING SIDE RAILS, END RAILS, A BOTTOM AND AN OPEN TOP ADAPTED TO RECEIVE A PRINTING FORM; A SEPARATE FRAME MEMBER ADAPTED TO TRAVEL FROM ONE EXTREMITY TO THE OTHER EXTREMITY OF SAID BOX FRAME AND HAVING A ROTARY IMPELLER EXTENDING TRANSVERSELY OF SAID BOX FRAME, SAID IMPELLER HAVING A PLURALITY OF TRANSVERSE ROWS OF CIRCUMFERENTIALLY MOUNTED IMPACT ELEMENTS OF SMALL SURFACE AREA, SAID ROWS BEING ADAPTED TO TRAVEL IN A CIRCULAR PATH ABOUT A CENTRALLY-DISPOSED COMMON AXIS AND SAID IMPACT ELEMENTS BEING ADAPTED TO MOVE TOWARD AND AWAY FROM SAID PATH AND IN SMALL ARCS FROM THE AXIS OF THE RESPECTIVE ROWS ON WHICH THEY ARE MOUNTED, THE IMPACTING SURFACES OF SAID ELEMENTS BEING CAPABLE OF EXTENDING BELOW AND ABOVE THE POSITION OF THE RELIEF OF THE PRINTING FORM IN THEIR EX- 